Since your a beginner get your self a Zinc call, i linked a couple below. they work and they aren't that expensive. PRACTICE PRACTICE PRACTICE... i would call in my garage till the neighbor couldn't stand it any more. it also helps to wear an ear plug when your practicing, it helps you hear what the duck is hearing. when you think you are getting good, get a tape recorder and record a few of your calls then listen to it, this will help you to also hear what the ducks are hearing.

be random, ducks all sound different and if you have 24 decoys sittin in front of you each duck will sound a little different.

be raspy, the hens are the ones that make the noise, a drake will rarely call, the old raspy hens especially lead the group and have the most voice.

less is more till the end of the season, only call when you see wing tips and tail feathers, give a couple squacks to get attention and then let the ducks decide if they wanna inspect, towards the end of the season they have heard everything under the sun so blow your lungs out.

Look into that zinc PH2 combo, thats how i started, now i have a $130 foiles call that really gets it done, but i would have sounded like crap if i hadn't practiced.